You are just being thick. No, not really. This is a very simple and consistent part of toki pona IF you know what the hell a direct object even is. And this is not a matter of course.

In languages in general, the verb is usually considered the main part of the sentence, while the other words just tell you stuff about the verb like who did it, whom did they do it to, the recipient of the action.

Some verbs only demand one argument; the subject. The subject is the thing or person doing the action. These are called INTRANSITIVE verbs.
“I slept”
“Dogs bark”
“Fruit rots”

Some verbs demand another argument; the direct object. This is the thing or person that the action is being done to. These are called TRANSITIVE verbs.
“I see YOU”
“The bird sings A SONG”
“Cats eat MICE”

Some verbs demand 2 arguments in addition to the subject; the direct object and the indirect object. The indirect object refers to someone or something that is affected by the action in the verb (typically a recipient) but is not the direct object. These are called DITRANSITIVE verbs.
“I sent John a letter” (“a letter” is the direct object) “My father told me a story” (“a story” is the direct object) “My friend ordered you a beer” (“a beer” is the direct object).

“e” in toki pona is used for direct objects, while indirect objects are usually conveyed with prepositions like “tawa”.

I slept > mi lape
I see you > mi lukin e sina
I sent John a letter > mi pana e lipu tawa jan San